1. Field of the Invention
The present invention relates to an optical interconnection device using wavelength division multiplexed lights.
2. Description of the Related Art
The use of an optical interconnection device is very effective in increasing a data throughput of a data connection system lying within or between devices of a computer system and a transmission-exchanger. The term optical interconnection means communication technology wherein optical signal transfer systems comprised of optical emitters, optical receivers and optical fibers are parallel-driven to transmit signals upon short-range data communication connections within/between the devices. Through the use of the optical interconnection, high-capacity data communication connections can be implemented with a small-sized device scale and with a low delay.
As examples reported up to now as to optical interconnection devices, may be mentioned, an example in which optical receivers and emitters and their driver circuits are brought into integration and utilized in combination with a signal processing circuit of a package different therefrom, an example in which elements for receiving and emitting a single optical signal are implemented in the same package as a signal processing LSI, an example in which individually-produced wavelength-multiplexed elements, wavelength-demultiplexing elements and a signal processing LSI are placed on another substrate, etc.
There are known, for example, IEEE PHOTONICS TECHNOLOGY LETTERS, Vol. 4, No. 6, June 1992, P614-617, “Operation of a Fully Integrated GaAs—AlxGa1-xAs FET-SEED: A Basic Optically Addressed Integrated Circuit”, T. K. Woodward et. al (fist prior art), the 1999 Communications Society Conference of the Institute of Electronics, Information and Communication Engineers, B-10-134, P311, “Optical interconnection Intellectual Property (OIP) for System-On-Chip LSIs”, Ryuji Yoshikawa, et. al (second prior art), IEEE 802.3 HSSG Interim Meeting, Idaho, June 1999, “WWDM Transceiver Module for 10-Gb/s Ethernet”, B. E. Lemoff (third prior art), and the like.
However, any of the reports does not disclose one wherein laser diodes, photo diodes, their driver circuits, optical multiplexers, optical demultiplexers and an electric signal processing circuit are not brought into integration on a single semiconductor substrate.
On the other hand, Japanese Patent Laid-Open No. Hei 8-32046 (fourth prior art) filled jointly by the inventors of the present application is known as one wherein they are brought into integration on the single semiconductor substrate. It discloses a photo-electron integration device wherein an optical demultiplexer, an optical multiplexer and an optical waveguide are respectively comprised of a compound semiconductor.
When it is desired to increase a communication data throughput of an optical interconnection device, a restriction on the number of electric wirings connecting between optical transmitting and receiving elements and a signal processing LSI constituting the optical interconnection device, and a data band produce a bottleneck upon increase in communication capacity.
With a view toward increasing the capacity for data communication connections between respective elements constituting an optical interconnection device, there are known two methods: one for increasing the number of wirings for connecting between constituent elements and another for increasing a modulation rate of each signal line. Even in the existing device, however, an LSI of 1000-pin class has already been used within the device. A subsequent drastic increase in the number of pins and an increase in the number of wirings are difficult in terms of the manufacturing cost.
Even in the case of the modulation rate, a modulation band itself of a transistor circuit can be enlarged up to the neighborhood of 20 GHz by use of a silicon germanium transistor. However, a limitation on a circuit characteristic of a glass epoxy or polyimide system printed board on which elements are hybrid-packaged, is the neighborhood of 2.5 GHz.
Therefore, the method of independently packaging the various elements employed in the devices described in the first through third prior arts, hybrid-packaging them on a printed board and increasing a data throughput of each device by a multi-pin connection of high-speed wirings encounters difficulties in obtaining an optical interconnection device for transmitting high-speed signals exceeding 1 Gbit per second every signals with satisfactory reproducibility.
In the technology of integrating the signal processing LSI and the optical receivers and emitters without having to use the wavelength multiplexing as in the second prior art, the number of inputtable/outputtable optical signals is restricted depending on the number of fibers capable of being taken out from one integrated package. Since the volume of a connector is large even if a fiber small in cable volume, such as a ribbon fiber is used, the number of fibers capable of being taken out from one package is limited to about 20. It is thus considered that only about 50 Gbit per second is obtained as the communication capacity.
When a device showing the third prior art is used wherein laser optical emitters, optical receivers and wavelength-division demultiplexing elements are brought into integration, particularly when it is desired to actually execute electric signal processing operations such as signal path switching, it is necessary to connect a signal processing LSI distinct from driver circuit elements for a laser and a photo diode. Further, electrical wiring connections to the signal processing LSI will produce a bottleneck and hence an increase in communication capacity is difficult as expected.
Japanese Patent Laid-Open No. Hei 8-32046 (fourth prior art) has firstly proposed the implementation of all of the signal processing circuit, laser optical emitters and receivers, optical multiplexing elements and optical demultiplexing elements on one semiconductor substrate. However, since the optical demultiplexer, optical multiplexer and optical waveguide are respectively comprised of the compound semiconductor, it is difficult to realize a small-sized multiplexed optical interconnection device.
A problem to be solved by the present invention is to make compatible between an increase in high-speed communication capacity of an optical interconnection device and an enlargement of a high-speed communication distance.
An object of the present invention is to provide a high-speed and small-sized optical interconnection device using wavelength-multiplexed lights suitable therefor.